PAPR of DFT-s-OTFS with Pulse Shaping

TL;DR

This paper analyzes the peak-to-average power ratio (PAPR) of DFT-s-OTFS with pulse shaping, deriving bounds and comparing resource allocation schemes, showing interleaved allocation reduces PAPR and simplifies transmitter design.

Contribution

It provides a comprehensive PAPR analysis of DFT-s-OTFS with different pulse shapes and resource allocations, including derived upper bounds and performance comparisons.

Findings

Interleaved resource allocation yields lower PAPR than block allocation.

Root raised cosine pulse results in higher maximum PAPR than rectangular pulse.

DFT-s-OTFS achieves similar BER performance to OTFS without DFT spreading.

Abstract

Orthogonal Time Frequency Space (OTFS) suffers from high peak-to-average power ratio (PAPR) when the number of Doppler bins is large. To address this issue, a discrete Fourier transform spread OTFS (DFT-s-OTFS) scheme is employed by applying DFT spreading across the Doppler dimension. This paper presents a thorough PAPR analysis of DFT-s-OTFS in the uplink scenario using different pulse shaping filters and resource allocation strategies. Specifically, we derive a PAPR upper bound of DFT-s-OTFS with interleaved and block Doppler resource allocation schemes. Our analysis reveals that DFT-s-OTFS with interleaved allocation yields a lower PAPR than that of block allocation. Furthermore, we show that interleaved allocation produces a periodic time-domain signal composed of repeated quadrature amplitude modulated (QAM) symbols which simplifies the transmitter design. Based on our analytical results, the root raised cosine (RRC) pulse generally results in a higher maximum PAPR compared to the rectangular pulse. Simulation results confirm the validity of the derived PAPR upper bounds. Furthermore, we also demonstrate through BER simulation analysis that the DFT-s-OTFS gives the same performance as OTFS without DFT spreading.